In various applications, composite structures are designed to withstand the currents and voltages of a lightning strike. This capability may be accomplished by spraying on conductive coatings or applying a metallic mesh or screen to the outer surface of the composite structure. While these methods and techniques may be suitable for dissipating electrical current along the X and Y axes (along the surface) of the composite structure, they may not be effective in dissipating electrical current in the Z direction (through the thickness) of the structure. Consequently, electrical current from a lightning strike or electrical short may flow through the composite structure and, if it is allowed to become localized in a specific area, the current may cause damage to the resin binder which secures the carbon fibers of the composite structure together, or the carbon fibers themselves. Therefore, by provision of a current path throughout the composite structure along the X, Y and Z axes, the electrical current does not become localized in the structure.
Nanotechnology has attempted to develop an effective method of providing Z-direction conductivity through a composite material. However, nanotechnology is expensive and inconsistent. Additionally, nanotechnology does not currently provide a three-dimensional lightning protection method for composite materials or structures. If a metallic wire is woven through the material or structure, because the wire has a coefficient of thermal expansion which is greater than that of the rest of the composite perform, the expanding wire induces stresses in the material and lead to micro-cracking. Moreover, if the wire is continuously woven from face to face throughout the fiber form, resin pockets may form within the material since the wire can lock the rest of the fibers in during the manufacturing process or weaving process thus not allowing the fibers to expand or conform during the thermal processing inherent in the resin setting.
Therefore, an electrically conductive structure throughout which electrically-dissipating materials are three-dimensionally woven to dissipate electrical current along the X, Y and Z axes of the structure is needed.